The world’s largest bitcoin exchange OKCoin has suspended some of its services indefinitely, following a malicious cyber attack from unknown hackers. Due to an increasing number of complaints on bitcoin forums and panels including Bitcointalk.org and Bitcoin Reddit, OKCoin, which processes almost 40% of all bitcoin trades, announced to its users: “OKCoin is currently suffering from malicious cyber attacks and as a result, some services may be suspended, Sorry for the inconvenience.â€